The present invention relates generally to the field of processing and displaying terrain texture maps using a digital imagery system. More particularly, the present invention relates to a system and method for providing digital image storage and representation through storing both absolute values and delta values to provide the images.
Virtual environment databases have traditionally included local areas of terrain, textured with either geo-specific photographic imagery or with geo-typical repeating imagery. In recent years however, continuous whole-earth terrain skinning algorithms have replaced the limited local-area terrain models. These algorithms have elevated the need for corresponding continuous whole-earth texturing mechanisms. While continuous whole-earth image datasets are available at 10-15 m resolution, they are costly, storage intensive, and too coarse for a wide variety of training tasks. Synthesizing higher-resolution imagery offers an attractive alternative, both in terms of cost and training utility. A technique for run-time synthesis of whole-earth high resolution terrain imagery, while minimizing unnatural repetition and other artifacts, may be used. This technique may also include run-time nested blending of multiple high resolution photographic insets.
Within the past couple of decades, technologies for producing continuous polygonal terrain meshes over arbitrarily large areas have become increasingly popular. In accordance with these algorithms, there has been a need to produce continuous terrain imagery over large areas as well. The demand for this is evident in many markets, including geographic information systems, visual simulation, entertainment, broadcast journalism, and web-based terrain browsing. Some image generator vendors added custom hardware support for large dynamic range texture mapping in their high-end systems (Cosman, M. A., 1994 and Tanner, C. C., Migdal, C. J., & Jones, M. T., 1998). For systems lacking custom hardware support, software-based mapping of terrain polygons to a correlated multi-resolution set of independent texture maps has achieved a similar result. Since large dynamic range texturing capabilities are now the norm for real-time systems, there exists a high demand for training-worthy high-resolution large area image content.
Satellite imagery currently provides continuous whole-earth coverage up to 15 meters in resolution. Although higher-resolution imagery is available for a large number of areas of interest throughout the world, the desire to achieve high-resolution coverage for the whole earth is not yet satisfied by commercial imagery. Furthermore, a complete coverage at one meter would require in excess of 500 trillion samples. Thus, it is necessary to consider a means of synthesizing high-resolution texture for the vast majority of the earth's surface. And it is desirable to seamlessly integrate high-resolution imagery into the synthetic backdrop.
The presentation of overlapping image data sets typically exhibits dissimilarities between neighboring data sets. An example of the dissimilarities occurs during juxtaposition of a high-resolution aerial photograph with a coarser-resolution satellite image. The discontinuity appears very unnatural and can result in negative training in a flight simulation environment. This discontinuity is generally minimized by blending, abutting, and/or nesting images. However, blending of images may result in loss of data integrity for the blended images, particularly where the images are stored as blended representations.
What is needed is a system and method for efficient run-time integration of high-resolution imagery into a synthetic background in a manner that minimizes discontinuities yet preserves data integrity. What is further needed is such a system and method configured to provide blended images and preserve the integrity of original images in a user-configurable system.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.